The goal of photospectrometry is retrieving spectral information of a source of electromagnetic radiation, e.g. a light source, often to be able to extract information about the source itself. Photospectrometry is widely used in the biological and pharmaceutical sciences to identify molecular structures or to detect the presence of certain molecules in gases and solutions. This can be done, among other techniques, by measuring the spectrum a sample under test emits after excitation with an energy source, as in Raman spectroscopy, or for example by measuring the absorption spectrum of a sample under test.
Traditionally two types of techniques are used to extract spectral information. The first type offers the cheapest solution and involves only looking at just one fraction of the spectrum. This solution can be implemented by combining an optical bandpass-filter with a single detector. The second type involves splitting the spectrum by means of prisms or other diffractive, refractive or interferometric optical components and directing the resulting spectrum, split in space, towards an array of detectors, each detector, when looking at the system as a whole, being responsive to only a portion of the total spectrum. Embodiments conform to this type of spectrometry can be found for example in EP-0205050. A similar technique described in WO 2007/115312 uses a dispersive optical component to split the spectral information in time allowing a single detector to measure the spectrum in time.
The above known types of detection techniques involve the use of extra optical components such as filters, or diffractive, refractive, interferometric or dispersive components, which increases the complexity and cost of a photospectrometer.